Neurostimulation is the surgical technique of neuromodulation involving the placement of electrodes on the spinal cord or peripheral nerves. The electrode for spinal cord stimulation is placed onto the dura (protective membrane of the spinal cord) through an incision and some small amount of bone removal to access the inside of the spinal canal. Alternatively, electrodes are placed on the peripheral nerves either via surgical exposure or via needle placement.
The wires from the electrode are then tunneled under the skin to the site of the IPG (implantable pulse generator).
The IPG contains the battery source and the circuitry for programmability to send the appropriate signals to the electrode. The wires are connected to the IPG and then the representative from the stimulator company programs the circuitry to send signals to maximize the effect from the electrodes.
Understanding What is Involved in Neurostimulation Treatment
Even though in many instances the stimulator provides a very meaningful reduction in the pain, this does not happen in everybody. That is why before you commit to a permanent implantation stimulation system (electrode, possible extensions and an implantable pulse generator (IPG))- you will have a trial to see if neurostimulation works for you. This is an excellent feature of neurostimulation treatment since it can be tried first before you commit to having a device implanted permanently. The trial period consists of 7-10 days of stimulation.
During that time you record notes to yourself to see if the stimulation reduces the use of pain medicine, allows you to do more activities than you had before, or just allows you to be more comfortable in your activities of daily living. If during this time period, you are quite satisfied with the results, then you plan for a permanent implantation.
Trial Procedure in Summary
There are two ways a stimulation trial can be conducted. One is with temporary precutaneous leads, and the other is with paddle leads. We will discuss both.
A) Trial with percutaneous leads.
The percutaneous stimulator trial procedure is a minimally invasive outpatient procedure performed under conscious sedation. Dr. Barolat generally does not perform this type of trial. We work with a group of pain specialists who perform the percutaneous(needle puncture) stimulator trial. The skin is pierced with a needle along the spine and then the electrical lead is threaded through that needle up the spinal canal until it reaches the target level of the spine that is to be stimulated. The wire is then hooked up to an outside energy source and programmer where it stimulates the lead in the spine. At that time the physician will ask you questions to determine if you feel the tingling sensation in the area of your pain. If it is does give you stimulation in the painful region, then the wires are taped to your body securely and covered with a bandage to protect it from getting contaminated. If it is not in the correct area then the physician slides the lead to a different area to get better stimulation.
Once the stimulator wire is taped in place you go to the recovery room for a short time while the sedation is wearing off. There in the recovery room the stimulator company representative programs the stimulator to give you the best pain relieving coverage. You wear the stimulator for 7-10 days. During that time period you are keeping close track of your pain levels, amount of pain medicine, and activity level. If during that time you decide it had a positive effect on any of those parameters then you get scheduled for a permanent implantation of an electrode and an IPG. We do not recommend a trial period longer than 10 days due to the increased risk of infection.
The risks of any procedure involving the inside of the spinal canal (epidural space) are the same which are: infection in the epidural space, dural puncture which can cause headaches, paralysis, bowel, and/or bladder control issues, bleeding, and numbness or other sensory changes in the legs or back.
B) Trial with paddle leads
In this instance the trial is performed in two surgical stages separated by about one week. In the first stage the paddle leads will be placed surgically. These are the leads that, if the trial is successful, will stay in place (unlike the percutaneous trial where the leads will most likely be removed). The leads are then hooked to a temporary extension cable which is brought through the skin. This procedure usually requires an overnight hospital stay. The stimulation is then tested for one week. One week later, the patient meets with Dr. Barolat and his team to assess the results of the trial. The next day there is a second surgical procedure ( usually on an outpatient basis). If the trial is successful, the procedure consists of connecting the implanted paddle leads with the pulse generator, which is then placed in a subcurtaneous pocket (see Permanent Implant section). The temporary extensions are discarded. If the trial is not successful, the paddle leads instead are removed and nothing is implanted.
Which form of trial is appropriate for me?
There are several considerations which come into play in the decision making process:
- A percutaneous trial does not require a "surgical intervention" since the electrode is placed through the needle.
- A trial with paddle leads is more invasive, since it requires a surgical intervention with limited bone removal.
- There are situations where a trial with percutaneous leads in not possible e.g. previous spine surgery at the level of insertion of the electrode, excessive scar tissue in the spine, spinal stenosis which could increase the risk of passing a needle into the spinal canal.
- A trial with the paddle leads simulates more closely what the "final stimulation" will be, since the leads are the ones that will be permanently placed.
- In general, paddle leads provide a better pattern of stimulation (see Permanent Implant Section).
- There are situations where the stimulation with the percutaneous leads can be difficult to achieve e.g. stimulation in the cervical spine and in the sacral nerve roots.
- The risks with the paddle lead trial are about the same as those with the percutaneous leads.
In most situations a trial with percutaneous leads is the most appropriate way to proceed. However all these different options will be discussed with you by Dr. Barolat and his team to provide the best approach for you.